Nested guard doesn't catch exception properly.

[Takashi Kato]

This should print Caught exception.

  (guard (ball
          (#f (display "Caught exception.")))
         (guard (ball
                 (#f (raise ball)))
                (raise 'exn)))

Found in: http://srfi.schemers.org/srfi-34/post-mail-archive/msg00001.html

[Takashi Kato]

It shouldn't print Caught exception.... Both exception handler uses #f thus it should go thought to the top level handler (means unhandled excepsion).

The original issue was that it went to infinite loop if users use reference implementation. However on Sagittarius it was handled properly from the beginning.